Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description adds substantial behavior beyond the annotations: it says to save the returned header/token, defines a 7-day session validity, a 7-day extension limit per refresh, a 30-day hard lifetime from initialization, and clarifies that request/delivery expiries are unchanged. This is rich lifecycle context that the annotations alone do not provide.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is compact and front-loaded: the trigger condition and action come first, followed by the operational details about saving the token and the lifetime limits. Every sentence carries relevant information.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a one-parameter tool with no output schema, it covers the session lifecycle, extension limits, and the need to save the returned header/token. Its main omission is the required idempotency_key parameter, which is not addressed anywhere in the description.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The schema has one required parameter, idempotency_key, with 0% description coverage, and the tool description never mentions it. With low schema coverage, the description should explain how to generate or reuse the idempotency key, but it leaves that parameter undocumented.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb and resource: renew the session before expiry using the current Mcp-Session-Id. This is precise and distinguishes it from the order/request/quote sibling tools, none of which manage sessions.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It clearly states when to use the tool: before session expiry. It does not name alternatives or explain what to do after expiry, but there are no obvious sibling alternatives for session renewal.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.